Device for measuring the mass of a flowing medium

ABSTRACT

A device for measuring the mass of a flowing medium which avoids measuring liquid components entrained in the medium. The device includes an interrupting body, which is accommodated upstream of the device, in a section of an air intake line that tapers in the flow direction, in order to filter out liquid components entrained in the flow by means of the interrupting body and to divert the liquid components from the measuring device. The invention is provided for measuring the mass of a flowing medium, in particular for measuring the intake air mass of internal combustion engines.

PRIOR ART

The invention is based on a device for measuring the mass of a flowingmedium. A device has already been disclosed (DE-OS 35 15 206) in which acapture element is provided in the vicinity of a measuring element in ameasurement conduit of the device in order to prevent the measuringelement from capturing dirt particles present in the air flow. The givenaccommodation of the capture element in the vicinity of the measuringelement produces a leeward area downstream of the capture element, whichshould prevent the measuring element from capturing dirt particles.Nevertheless, when liquid components are entrained in the air flow, adeposit on the measuring element can be produced, which leads to adisadvantageous alteration of the characteristic curve or themeasurement precision of the device.

ADVANTAGES OF THE INVENTION

The device according to the invention for measuring the mass of aflowing medium, has the advantage over the prior art that the measuringelement is prevented from capturing in particular liquid components fromthe air flow so that a uniformly precise measurement result can occur.

Advantageous improvements and updates of the device are possible bymeans of the measures taken herein. It has turned out that in particulara prismatic embodiment of an interrupting body advantageously produces aparticularly effective diversion of liquid components entrained in theair flow. It is of particular advantage that a channel-shaped recess isprovided on an end face of the prismatic interrupting body in which theliquid components can collect in order to then drip away in thedirection of a wall of the intake line disposed opposite the device,without influencing the device.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is represented in a simplifiedform in the drawings and will be explained in detail in the descriptionbelow.

FIG. 1 shows a cross section through an intake line with a device andinterrupting body accommodated in it,

FIG. 2 shows a longitudinal section along a line II--II in FIG. 1,through the intake line with the device and interrupting body, and

FIG. 3 shows a top view of the intake line with the interrupting body.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

FIG. 1 shows a cross section of a device identified with 1, which isused to measure the mass of a flowing medium, in particular the intakeair mass of internal combustion engines. The internal combustion enginecan be a mixture compressing engine with externally supplied ignition,or it can be an air compressing, self-igniting engine. As shown in moredetail in FIG. 2, a longitudinal section along a line II--II in FIG. 1,the device 1 preferably has a slim, rod-shaped, block-like form thatextends longitudinally in the direction of a plug axis 10, and isinserted, for example so that it can slide, into an opening 6 let into awall 5 of an intake line 7 that constitutes a flow line. The wall 5depicted with cross hatching is for example a part of cylindricallyembodied intake line 7, through which a medium flows, in particular theair aspirated by the internal combustion engine. The wall 5 of theintake line 7 defines a flow cross section which in the instance of thecylindrical intake line 7 has a circular cross section, in the center ofwhich a center axis 11 extends in the direction 18 of the flowingmedium, parallel to the wall 5, and is oriented perpendicular to theslide axis 10. The direction of the flowing medium is indicated in FIGS.1 and 2 by means of corresponding arrows 18 and runs from left to rightthere.

The device 1 protrudes into the flowing medium with a part called themeasurement part 17 below. In the measurement part 17 of the device 1, ameasurement conduit 20 is embodied in which a measuring element 21 isaccommodated for measuring the medium flowing in the intake line 7. Thedesign of a device 1 of this kind is sufficiently known by one skilledin the art, for example from DE-OS 44 07 209, whose disclosure should bea component of the current patent application.

According to the invention, upstream of the device 1, an interruptingbody 25 is accommodated in the intake line 7 and its shape is embodiedso that components entrained in the flow 18 of the medium, in particularthose in liquid form, are diverted away from the center of the intakeline 7 indicated by the center axis 11 essentially to a lower part ofthe wall 5 that is represented at the bottom in FIG. 2 and is identifiedwith the reference numeral 8. As shown in more detail in FIG. 1, thevertically disposed interrupting body 25 has a prismatic form for thispurpose, with an essentially triangular cross sectional area, which isdefined by two side faces 29 and an end face 26 that is disposed inopposition to the flow 18. A slightly concave arched, channel-shapedrecess 27 is provided on the end face 26 oriented toward the flow 18 andliquid components disposed in the flow 18 can collect in this recess andthen can flow in the channel-shaped recess 27 out toward the part 8 ofthe wall 5 that is disposed opposite the device 1 and is depicted at thebottom in FIG. 2, so that the liquid components are prevented frominfluencing the flow in the measurement conduit 20 of the device 1. Theinterrupting body 25 is accommodated in a section 30 of the intake line7 that tapers down in a nozzle-shaped fashion in the flow direction 18and reduces the cross section of the intake line 7. Preferably, the sidefaces 29 that lead from the end face 26 and approach each other in theflow direction 18 extend approximately parallel to the arched wall 5 ofthe section 30 of the intake line 7 and meet for example at the centeraxis 11. The section 30 of the intake line 7 that tapers in the flowdirection 18 constitutes a convergent nozzle section in which anacceleration or an increase of the flow speed of the medium occurs. Theembodiment of the interrupting body 25 is carried out in such a way thata flow around the interrupting body 25 occurs essentially without flowseparations at this point. Fluid and solid particles cannot follow thedeflection and in particular, fluid impurities collect in thechannel-shaped recess 27 so that downstream of the interrupting body 25,these impurities are prevented from soiling the device 1 or themeasuring element 21. The device 1 is accommodated in the intake line 7,downstream of the section 30 and downstream of an extremely narrow crosssection 33 that adjoins the section 30. Preferably, the device 1 isaccommodated in relative proximity to the interrupting body 25, whereina distance a of the device 1 from the interrupting body 25, measured inthe flow direction 18, corresponds approximately to one to three timesthe width b of the interrupting body 25, measured in the flow direction18.

The interrupting body 25 extends parallel to and flush in the flowdirection 18 to the slide axis 10 and therefore perpendicular to thecenter axis 11, from the upper wall 5 preferably to the lower part 8 ofthe wall 5. As shown in more detail in FIG. 3, a top view of theinterrupting body 25 accommodated in the intake line 7, in the region ofthe lower part 8 of the wall 5, an opening 31 that extends in the flowdirection 18 is let into the interrupting body 25. The opening 31, whichis provided on the interrupting body 25, on an end 28 disposed oppositethe opening 6 for the device 1, for example has a semicircular crosssection which the fluid components collected in the channel-shapedrecess 27 can flow out of once again, which are then transported awayfrom the flow and in the course of this, through the influence ofgravity, remain essentially in the region of the lower part 5 of thewall 8. It is also possible, though, to embody the interrupting body 25from the upper wall 5 only until it reaches the vicinity of the lowerpart 8 of the wall 5 so that a gap 32, which is indicated with a dashedline 35 in FIG. 3, remains at the end 28 of the interrupting body 25 inrelation to the lower part 8 of the wall 5, which the liquid componentscollected in the channel-shaped recess 27 can drip out of and toward thelower part 8 of the wall 5.

The rod-shaped interrupting body 25 is therefore disposed upstream ofthe device 1, which is likewise embodied as rod-shaped and protrudinginto the intake line 7, wherein at least the part of the measurementconduit 20 that extends approximately at the level of the center axis 11is disposed, along with the measuring element 21, in the lee of theinterrupting body 25. The interrupting body 25 and the device 1 extendfor example parallel to each other through the center axis 11 of theintake line 7. The disposition of the interrupting body 25 in thesection 30 that tapers in the flow direction 18 means that no whorls areproduced due to variations in the boundary layer, which would lead tomeasurement errors in the device 1. For improved removal of deposits inthe recess 27, the bottom of the recess 27 oriented downstream isinclined in the direction of the flow 18 and toward the end 28, and theopening 31 or the gap 32 tapers in the flow direction 18.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

What is claimed is:
 1. An airflow measuring device for measuring themass of a flowing medium of the intake air flowing in an intake line ofinternal combustion engines, said airflow measuring device (1) protrudesinto the intake flow line, said airflow measuring device includes ameasuring element (21) for measuring the mass flowing in the intake flowline, upstream of the airflow measuring device (1) an interrupting body(25) is accommodated at a tapered air inflow section (30) of the intakeflow line (7) on an axis (11), and said interrupting body has anupstream end face (26), beginning at the upstream end face (26) theinterrupting body tapers in the airflow direction (18) of the mediumfrom an air input end toward said airflow measuring device, and saidinterrupting body (25) is disposed totally with a width (b) in saidtapered section (30) of the intake flow line (7) measured in the flowdirection (18) of the air flow.
 2. An airflow measuring device accordingto claim 1, in which the interrupting body (25) has a prismatic shapewhich extends to a point on the axis (11) in a direction of air flow. 3.An airflow measuring device according to claim 2, in which an airflowinput end face (26) of the interrupting body (25) oriented toward theflow (18) has a concave channel-shaped recess (27).
 4. An airflowmeasuring device according to claim 3, in which the interrupting body(25) is accommodated in relative proximity to the airflow measuringdevice (1), wherein a distance (a) of the airflow measuring device (1)from the interrupting body (25), measured in the flow direction (18),corresponds approximately from about one to three times width (b) of theinterrupting body (25), measured in the flow direction (18).
 5. Anairflow measuring device according to claim 2, in which the interruptingbody (25) is accommodated in relative proximity to the airflow measuringdevice (1), wherein a distance (a) of the airflow measuring device (1)from the interrupting body (25), measured in the flow direction (18),corresponds approximately from about one to three times width (b) of theinterrupting body (25), measured in the flow direction (18).
 6. Anairflow measuring device according to claim 2, in which said tapered airflow section 30 of said inflow line has a surface which is substantiallyparallel with the prismatic surface of the interrupting device.
 7. Anairflow measuring device according to claim 1, in which the upstream endface (26) of the interrupting body (25) is oriented toward the air inputflow (18) and has a concave channel-shaped recess (27).
 8. An airflowmeasuring device according to claim 7, in which the interrupting body(25) is disposed vertically and on a lower end (28), said interruptingbody has an opening (31) connected with the concave channel-shapedrecess (27).
 9. An airflow measuring device according to claim 8, inwhich the interrupting body (25) is accommodated in relative proximityto the airflow measuring device (1), wherein a distance (a) of theairflow measuring device (1) from the interrupting body (25), measuredin the flow direction (18), corresponds approximately from about one tothree times width (b) of the interrupting body (25), measured in theflow direction (18).
 10. An airflow measuring device according to claim7, in which the interrupting body (25) is disposed vertically with anupper end connected to an inner face of said intake flow line and alower end (28) of said interrupting body is spaced from a lower part (8)of a wall (5) of the flow line (7) by a gap (32).
 11. An airflowmeasuring device according to claim 5, in which the interrupting body(25) is accommodated in relative proximity to the airflow measuringdevice (1), wherein a distance (a) of the airflow measuring device (1)from the interrupting body (25), measured in the flow direction (18),corresponds approximately from about one to three times width (b) of theinterrupting body (25), measured in the flow direction (18).
 12. Anairflow measuring device according to claim 7, in which the interruptingbody (25) is accommodated in relative proximity to the airflow measuringdevice (1), wherein a distance (a) of the airflow measuring device (1)from the interrupting body (25), measured in the flow direction (18),corresponds approximately from about one to three times width (b) of theinterrupting body (25), measured in the flow direction (18).
 13. Anairflow measuring device according to claim 1, in which the interruptingbody (25) is accommodated in relative proximity to the airflow measuringdevice (1), wherein a distance (a) of the airflow measuring device (1)from the interrupting body (25), measured in the flow direction (18),corresponds approximately from about one to three times width (b) of theinterrupting body (25), measured in the flow direction (18).
 14. Anairflow measuring device according to claim 1, in which said tapered airflow section (3) of said inflow line has a surface which issubstantially parallel with the prismatic surface of the interruptingbody.